1. Field of the Invention
This invention relates to a vacuum assisted multiple position walking beam apparatus, which precisely advances and locates products, which are placed and advanced thereon in a row for straight line production operations.
2. Description of the Prior Art
In the Photovoltaic industry silicone wafers or cells are assembled into panels by arranging them in an x-y matrix. This process has been accomplished manually and through the use of automation. The automation concepts can be summarized into two basic methods. The first method is commonly referred to as matrixing, and involves placing each cell into a grid fixture one at a time, and then moving the grid around to solder each cell together. The second approach is commonly referred to as stringing, and involves placing and soldering each cell into a row of the matrix individually, thereby forming xe2x80x9cstringsxe2x80x9d of cells. These strings can then be placed into storage buffers or placed directly onto a glass to form the panel. The stringing method represents a more compact solution which ultimately requires less floor space, and is gaining popularity in the industry. The automation that is currently available for stringing solar cells utilizes a metal belt to transport the string as it is being constructed. Many problems exist with the metal belt apparatus, which include belt tracking, belt warpage, belt life, difficulty in precisely holding and supporting the wafers as they are transported and soldered, and the expense involved in maintaining and operating the equipment.
The multiple position vacuum assisted walking beam apparatus of the invention is useful in the photovoltaic industry and any industry in which wafer like products must be precisely located and advanced in a straight line for processing, which apparatus provides precision location, advancement and holding of the products for processing without the problems of previously available equipment.
In developing apparatus for assembling strings of photovoltaic cells several criteria were involved. The apparatus must maintain the alignment of the cells as they are placed next to each other, must not touch or damage the cell edges, and must be easily configured for different cell sizes and string lengths. Because the cell edges are fragile, a concept was required that would not involve touching the cell edges to move the cell or string. Vacuum was selected as the best method to grip or hold the cell after it was placed into the string. The walking beam concept was selected for transporting and processing the strings, which included a movable center beam, and two stationary side beams. With a conventional walking beam mechanism, two separate beams are utilized. One beam remains stationary while the other beam moves up and down in the vertical axis and back and forth in the horizontal axis. The moving beam will lift the string from the stationary beam, carry the string forward, lower the string onto the stationary beam, move below the level of the string, and retract to the home position. In order to hold the cells, vacuum was added to both the moving beam, and the stationary beams. Vacuum switching was provided to operate when the moving beam was exactly coplanar with the stationary beams, so the cell was not pulled by the vacuum and broken. To solve this problem, a third position was introduced to the center beam. The moving center beam therefor has three vertical positions described as; above the stationary beams, coplanar with the stationary beams, and below the stationary beams. Vacuum is directed into the moving beam when the string is being lifted, carried forward, and lowered to the coplanar position. When the moving center beam is coplanar with the stationary beams vacuum is switched from the moving beam to the stationary beams and the string/cells is/are then anchored to the stationary beams. The moving beam, now without vacuum, is free to drop below the string and retract in preparation for the next move. At this time, the next cell is placed on the stationary beams and soldered to the adjacent cell. The string is always held by vacuum whether it is held to the stationary beams or held to the moving beam. At no time is the string without vacuum. This is important as the aesthetics and performance of the solar module are due in part to the alignment and positioning of the cells within the module.
It has now been found that a multiple position vacuum assisted walking beam apparatus can be constructed, which has wafer like products placed thereon, which apparatus includes a movable center beam and fixed side beams, one on each side of the center, with vacuum selectively applied to the center beam and the side beams to support the products as they are transported and processed.
The principal object of the invention is to provide a vacuum assisted multiple position walking beam apparatus for support, attachment, and transport of products in a string configuration.
A further object of the invention is to provide apparatus of the character aforesaid which is precise and positive in operation.
A further object of the invention is to provide apparatus of the character aforesaid which is of rigid construction.
A further object of the invention is to provide apparatus of the character aforesaid which is resistant to wear and fatigue.
A further object of the invention is to provide apparatus of the character aforesaid, which is useful with a wide variety of products and manufacturing operations.
A further object of the invention is to provide apparatus of the character aforesaid, which is simple to construct but rugged and long lasting in service.
Other objects and advantageous features of the invention will be apparent from the description and claims.